Unable to Convert Windows 10 LTSB Build 14393 from MBR to GPT

Hello,

I am having some issues trying to convert a disk from MBRto GPT by using the following command in Admin Powershell “mbr2gpt.exe /convert/AllowfullOS”. My company has introduced a new image called Windows LTSB Build14393 that we are wanting to use as our “base image”, since this particularbuild strips away all the “Extra” stuff such as edge, Microsoft store, etc etc.
Anyways, the problem I am running into is the followingcommand:
“mbr2gpt.exe /convert /AllowfullOS”
It states that the following file isn’t specified. Afterdoing some research online, I found a post on Microsoft’s website that statesthe following command is only compatible in builds 1703 or higher. The reasonbehind us needing to convert the disk from MBR to GPT is so UEFI can be turnedon while the drive is encrypted with bitlocker. Otherwise every time you rebootor make a simple change in the BIOS, bitlocker is going to prompt for therecovery key…
Is there some type of third party tool that can be used toconvert a disk to GPT? Or perhaps some type of “Work Around”?
Any help at this point would be greatly appreciated!

AndreTen said:

Ed's suggestion is probably the best, since you get (and probably have) system image.

Other solution is to use Minitool partition wizard, but Pro version is required for converting system disk. Did you consider using WinPE environment? Not sure about possible bitlocker problems using newer Windows environemet.
Check this Minitool page

AndreTen,

Yes, I moved the mbr2gpt installer to a WinPE environment and tried to run the installer that way... It said it completed successfully but still couldn't boot to the hard disk when UEFI was turned on. I'll try Ed's suggestion to see if that helps.

I see an issue may be that the LTSB is an Enterprise edition of Win10.
Quoted from Windows 10 editions - Wikipedia

Long-Term Servicing Branch (LTSB)This branch is exclusively available for Windows 10 Enterprise LTSB edition and distributes snapshots of this edition that are updated every 2-3 years. LTSB builds adhere to Microsoft's traditional support policy which was in effect before Windows 10: They are not updated with new features, and are supported with critical updates for 10 years after their release. Microsoft officially discourages the use of LTSB outside of "special-purpose devices" that perform a fixed function and thus do not require new user experience features. As a result, it excludes Windows Store, most Cortana functionality, and most bundled apps (including Microsoft Edge).^[6][1][3] According to a Microsoft announcement, this branch will be renamed Long-Term Servicing Channel (LTSC) in 2019, to match the name changes mentioned above.

The Build number 14393 suggests the Version is 1607, we now have Versions 1703 and 1709 with 1809 probably later this year. Version numbering is Year and Month of release.

manofskill said:

The reasonbehind us needing to convert the disk from MBR to GPT is so UEFI can be turnedon while the drive is encrypted with bitlocker. Otherwise every time you rebootor make a simple change in the BIOS, bitlocker is going to prompt for therecovery key…

You'll get no advantage from doing this.

If you change BIOS setting you will be prompted for a recovery key exactly the same if you are booting in UEFI or legacy mode (I run bitlocker on both types of system). This is the point of bitlocker - to stop unauthorized changes to the boot process and it works exactly the same with legacy and UEFI.

If you want to make a change to a BIOS setting then the correct procedure is to suspend bitlocker, reboot, make your change and then once you get back to desktop bitlocker is re-enabled.

Suspend or Resume BitLocker Protection for Drive in Windows 10 Windows 10 Tutorials